Disturbances of memory, behavior, cognition, and seizures can result from immune-mediated encephalitis. One cause of autoimmune encephalitis is the paraneoplastic manifestation of a neoplasm. Most paraneoplastic encephalitides have been associated with antibodies to intracellular onconeuronal proteins and cytotoxic T-cells presumably against the same proteins. These disorders usually associate with malignant tumors and are poorly responsive to immunotherapies or treatment of the cancer.
In recent years, a severe but often reversible encephalitis of unknown etiology that predominantly affects young women has been increasingly recognized. The disorder has received several names, including acute diffuse lymphocytic meningoencephalitis, acute reversible limbic encephalitis, acute juvenile female non-herpetic encephalitis, or juvenile acute non-herpetic encephalitis. Since most patients develop a prodromic viral-like illness, a postinfectious immune-mediated etiology has been postulated.
The affected patients were women who developed prominent psychiatric symptoms, seizures, memory deficits, and decreased level of consciousness often requiring ventilatory support. Three salient features included the young age of the patients, the association with ovarian teratomas, and the detection of antibodies to unknown antigens predominantly expressed in the cell membrane of hippocampal neurons (also referred to as a subgroup of neuropil antigens).
A better understanding of the function of the paraneoplastic neuronal (or onconeuronal) antigens may help improve the treatment strategies. For the clinician who currently confronts these patients, however, the best chance to affect the neurologic outcome depends on: (1) the prompt diagnosis of the disorder, (2) the early discovery and treatment of the tumor, and (3) the use of immunotherapy. Accordingly, a need exists for reliable methods of diagnosing and treating autoimmune encephalitis or epileptic seizures.